This proposal will evaluate the effect of treatment for hyperglycemia on cognitive and emotional functioning in elderly patients with Non-Insulin- Dependent Diabetes Mellitus (NIDDM). Evidence is accumulating that poor glycemic control may have untoward effects on cognitive and emotional processes in older diabetics. However, results to date have been correlational. To our knowledge, there have been no treatment studies evaluating the effect of diabetic treatment on higher level cognitive function. Since several studies have suggested that improvement in both neuropathy and retinopathy can occur when good metabolic control is established, one could hypothesize that similar positive changes in behavioral functioning due to treatment might also be expected. This hypothesis will be tested using a two-group (treatment/placebo) double- blind treatment paradigm, including a single-blind partial crossover for the placebo group. Sufficient subjects will be recruited and screened over a five-year period to have 60 patients in each group (with replacement). Male or female NIDDM outpatients (60-80 yrs) will be accepted for the study if they have a Fasting Plasma Glucose (FPG) greater than or equal to 150 mg/dl, are less than 150% of ideal body weight have no history of drug abuse, alcoholism or psychiatric disorder and are able to complete the behavioral measures. They must also have no history of ketoacidosis or insulin treatment, no significant hepatic disease, no significant renal dysfunction or nephropathy, no history of sensitivity to sulfa drugs, and no history or presence of significant medical disorder that could affect the results of the study. Patients meeting criteria will be randomly assigned to the treatment or placebo condition. Pretreatment administration of dependent measures will be completed after which patients will receive glipizide or a placebo for a three month period. Dependent variables include measures of Learning and Memory, Attention, Visual/Motor Functioning, Abstract Reasoning, Depression, Anxiety, General Psychopathology, Social Functioning, HbAlc nad FPG. After post-treatment measures are obtained, patients in the placebo condition will be crossed over to the treatment condition; patients in the treatment condition will continue medication. Dependent measures will be obtained again after three months; two follow-up evaluations will then be completed at three month intervals.